jdbm.recman

Class FreeLogicalRowIdPage

java.lang.Object

jdbm.recman.PageHeader

jdbm.recman.FreeLogicalRowIdPage

All Implemented Interfaces:

BlockView

class FreeLogicalRowIdPage
extends PageHeader

Class describing a page that holds logical rowids that were freed. Note that the methods have *physical* rowids in their signatures - this is because logical and physical rowids are internally the same, only their external representation (i.e. in the client API) differs.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) static short	ELEMS_PER_PAGE The number of elements by page
private static short	O_COUNT The offset for the number of free pages
(package private) static short	O_FREE Offset of the number of free row Ids
(package private) PhysicalRowId[]	slots

Fields inherited from class jdbm.recman.PageHeader

blockIo, SIZE

Constructor Summary

Constructors

Constructor and Description
FreeLogicalRowIdPage(BlockIo blockIo) Constructs a data page view from the indicated block.

Method Summary

Modifier and Type	Method and Description
(package private) PhysicalRowId	alloc(int slot) Allocates a slot
(package private) void	free(int slot) Frees a slot
(package private) PhysicalRowId	get(int slot) Returns the value of the indicated slot
(package private) short	getCount()
(package private) int	getFirstAllocated()
(package private) int	getFirstFree() Returns first free slot, -1 if no slots are available
(package private) static FreeLogicalRowIdPage	getFreeLogicalRowIdPageView(BlockIo blockIo) Factory method to create or return a data page for the indicated block.
private boolean	isAllocated(int slot) Returns true if a slot is allocated
private boolean	isFree(int slot) Returns true if a slot is free
private void	setCount(short i) Sets the number of free rowids
private short	slotToOffset(int slot) Converts slot to offset
java.lang.String	toString()

Methods inherited from class jdbm.recman.PageHeader

getMagic, getNext, getPrev, getView, paranoiaMagicOk, setNext, setPrev, setType

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

O_COUNT

private static final short O_COUNT

The offset for the number of free pages

See Also:

Constant Field Values

O_FREE

static final short O_FREE

Offset of the number of free row Ids

See Also:

Constant Field Values

ELEMS_PER_PAGE

static final short ELEMS_PER_PAGE

The number of elements by page

See Also:

Constant Field Values

slots

final PhysicalRowId[] slots

Constructor Detail

FreeLogicalRowIdPage

FreeLogicalRowIdPage(BlockIo blockIo)

Constructs a data page view from the indicated block.

Method Detail

getFreeLogicalRowIdPageView

static FreeLogicalRowIdPage getFreeLogicalRowIdPageView(BlockIo blockIo)

Factory method to create or return a data page for the indicated block.

getCount

short getCount()

Returns:

the number of free rowids

setCount

private void setCount(short i)

Sets the number of free rowids

free

void free(int slot)

Frees a slot

alloc

PhysicalRowId alloc(int slot)

Allocates a slot

isAllocated

private boolean isAllocated(int slot)

Returns true if a slot is allocated

isFree

private boolean isFree(int slot)

Returns true if a slot is free

get

PhysicalRowId get(int slot)

Returns the value of the indicated slot

slotToOffset

private short slotToOffset(int slot)

Converts slot to offset

getFirstFree

int getFirstFree()

Returns first free slot, -1 if no slots are available

getFirstAllocated

int getFirstAllocated()

Returns:

The first allocated slot, -1 if no slots are available.

toString

public java.lang.String toString()

Overrides:

toString in class PageHeader